Chinese scientists announced they’ve invented a new kind of coating for aircraft and other weapons that’s virtually undetectable by radar…

This new, lab-made “metamaterial,” in essence a very fine mesh with microscopic etchings, could shrink the radar signature of a fighter jet, warship, or missile by a thousand times, claimed the scientists at the Chengdu-based Institute of Optics and Electronics, part of the Chinese Academy of Sciences.

If the Chinese team led by professor Luo Xiangang is telling the truth and their metamaterial works like they’ve claimed, China might seem poised to become the world leader in stealth technology, leapfrogging the United States and effectively canceling out a major American military advantage.

But there are good reasons to be very skeptical.

“As with many new technologies, there is sometimes a little hype when reporting preliminary results.”

— Sir John Pendry, professor at Imperial College London

Metamaterials such as the Chinese mesh are not exactly new. But they’re new enough that their promise often exceeds their actual performance and usefulness. “As with many new technologies, there is sometimes a little hype when reporting preliminary results,” Sir John Pendry, a professor at Imperial College London, told The Daily Beast.

Pendry knows what he’s talking about. Back in the mid-1990s, he invented the first metamaterial. A metamaterial is any man-made substance—an exotic metal alloy, for example—that displays properties not normally found in nature. Like the ability to disappear to the naked eye, or on radar.

Luo and his colleagues at the Institute of Optics and Electronics didn’t actually make any of their stealth mesh. Rather, they created a mathematical model that describes a metamaterial with incredible stealth qualities.

In a mid-July official notice first widely reported by the Hong Kong South China Morning Post, the Chinese researchers claimed their mesh could reduce, by up to a thousand times, the radar signature of an object across a swath of the electromagnetic spectrum from 0.3 to 40 gigahertz.

Many military radars operate at around 10 gigahertz, meaning the Chinese metamaterial in…